The only reason for supporting of HD-DVD is based upon price, which is of course important for companies involved if hardware and disc manufacture. With regards to consumers, HD-DVD hardware maybe initially cheaper but I bet you won't find HD-DVD's are that much cheaper, if at all, than Blue-ray DVD's. Companies will always try to maximise profit, so if a blue-ray DVD retails for £19.99 then HD-DVD will probably sell for £18.99, they are not going sell for £14.99 and loose profit.
On paper, excluding price, Blue-ray is by far the superior format. It has a larger capacity which can be used for better picture and sound quality whether they decide to use MPEG 2 or MPEG4 encoding and the interactive capabilities of the format are better.
However we all know that a better format (Beetamax) doesn't mean it will take market share.
I think both formats will co-exist with dual HD-DVD and Blue-ray players in due course. However availability of software will probably define which format is more successful.